1. Field of the Invention
The present invention generally relates to the transmission of digital information and more particularly to a system and a method for serial transmission of binary signals, i.e. binary-coded information.
2. Description of the Prior Art
For so-called modem transmission of digital information by a two-wire connection, there are a number of standardized methods. Frequency shift modulation is used up to 1200 baud and, at higher rates, differential phase shift modulation is used, possibly together with amplitude modulation.
The highest transmission rate standardized for two-wire connections is 48 kilobaud (cf. CCITT recommendation V35). In this instance, it is necessary to use relatively complicated transmitters and receivers with, for instance, automatic adaptive equalization of the characteristics of the transmission channel. In addition, in order to maintain the synchronism between transmitter and receiver one has to resort to so-called scrambling, which ensures a sufficiently frequent bit alternation.
By using carrier frequency systems, it is possible to obtain transmission rates considerably higher than those indicated above. However, such systems necessitate the use of complicated appliances on both the transmitter and the receiver side, as well as more expensive lines, for instance coaxial cables.